[Yeap, W. S.; Bevk, D.; Vanderzande, D.; Lutsen, L.; Maes, W.; Haenen, K.] Hasselt Univ, Inst Mat Res IMO, B-3590 Diepenbeek, Belgium. [Bevk, D.; Vanderzande, D.; Lutsen, L.; Maes, W.; Haenen, K.] IMOMEC, IMEC Vzw, B-3590 Diepenbeek, Belgium. [Liu, X.; Fahlman, M.] Linkoping Univ, Dept Phys Chem & Biol, S-58183 Linkoping, Sweden. [Krysova, H.; Kavan, L.] Acad Sci Czech Republic, J Heyrovsk Inst Phys Chem, Vvi, CZ-18223 Prague 8, Czech Republic. [Pasquarelli, A.] Univ Ulm, Inst Elect Devices & Circuits, D-89069 Ulm, Germany.

N3 dye molecules [cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)ruthenium(II)] are covalently attached to boron-doped nanocrystalline diamond (B:NCD) thin films through a combination of coupling chemistries, i.e., diazonium, Suzuki, and EDC-NHS. X-ray and ultraviolet photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy are used to verify the covalent bonding of the dye on the B:NCD surface (compared to a hydrogen-terminated reference). The spectroscopic results confirm the presence of a dense N3 chromophore layer, and the positions of the frontier orbitals of the dye relative to the band edge of the B:NCD thin film are inferred as well. Proof-of-concept photoelectrochemical measurements show a strong increase in the photocurrent compared to non-dye-functionalized B:NCD films. This study opens up the possibility of applying N3-sensitized B:NCD thin films as hole conductors in dye-sensitized solar cells.

Donor–acceptor type light-harvesting molecular wires are covalently attached to a boron-doped diamond surface via a combination of diazonium electrografting and Suzuki cross-coupling. For the Suzuki reaction, various catalytic systems are compared with respect to their imposed surface coverage. Combining 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (SPhos) and Pd(0), the diamond coverage improves considerably (by 98%) as compared to the standard tetrakis(triphenylphosphine)palladium(0) (Pd(PPh3)4) catalyst. As the energy levels between the molecular chromophores and the diamond film align well, the sophisticated functionalized diamond surfaces present a first step towards the development of fully carbon-based devices for light to electricity conversion.

The thiazolo[5,4-d]thiazole fused (bi)heterocycle is an electron deficient system with high oxidative stability and a rigid planar structure, enabling efficient intermolecular pi-pi overlap. The parent thiazolo[5,4-d]thiazole moiety hence already possesses some appealing features towards applications in organic electronics. Moreover, aryl-functionalized thiazolo[5,4-d]thiazole derivatives - expanding the conjugated backbone of the semiconducting material - are easily prepared. Surprisingly, interest in thiazolo[5,4-d] thiazole-based materials has been rather low, until quite recently, when the high potential of these molecules was widely recognized, notably in the field of organic photovoltaics. Despite the almost exponential growth of activity, the synthetic chemistry behind these molecules has only been explored to a minor extent and there is plenty of room for improvement and broadening of the material scope. In this review, an overview of the currently available synthetic methods and the range of materials prepared to date, together with their basic material properties and main applications, is provided, with the aim to facilitate and stimulate further progress in thiazolo[5,4-d]thiazole-based materials science.

A two-step synthetic protocol involving (i) a Wittig-type carbonyl olefination, and (ii) regioselective alkylation of the exocyclic double bond with LiAlH4 and an alkyl bromide, was developed as an alternative to the recently reported three-step synthetic approach toward asymmetrically substituted/functionalized 4H-cyclopenta[2,1-b:3,4-b′]dithiophenes. The two routes are rather complementary, with specific advantages depending on the desired substitution pattern, and are of particular appeal for the construction of semiconducting materials to be applied in organic photovoltaics.

In this Letter we report on the reaction of 4H-cyclopenta[2,1-b:3,4-b′]dithiophen-4-one with various trivalent organophosphorus derivatives, with an emphasis on the final products depending on the applied reagents. No reaction occurred upon treatment with either triphenyl- or tricyclohexylphosphine, whereas addition of triethyl phosphite or tri(n-butyl)phosphine resulted in pinacol rearrangement. Structure elucidation of the isolated 5H-spiro(benzo[1,2-b:6,5-b′]dithiophene-4,4′-cyclopenta[2,1-b:3,4-b′]dithiophen)-5-one was achieved by combined NMR experiments, theoretical chemical shift and geometry calculations, and single crystal X-ray analysis.

The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opto-electronic characteristics of the polythiophene donor material can be modified to a certain extent via copolymerization without (too much) jeopardizing the OPV efficiency, as far as the functionalized side chains are introduced in a moderate ratio (<30%) and that preference is given to side chains with a small molar volume. A range of complementary techniques – UV–Vis spectroscopy, (modulated temperature) differential scanning calorimetry, transmission electron microscopy and X-ray diffraction analysis – indicated that variations in polymer crystallinity, while maintaining a high level of regioregularity, are probably the main factor responsible for the observed differences.

Two variations of a parallel solution-phase synthesis of N-substituted dimethyl 4-oxo-1,4-dihydropyridine-3,5-dicarboxylates 4 and methyl 3-oxo-3,5-dihydro-2H-pyrazolo[4,3-c]pyridine-7-carboxylates 9 from dimethyl acetone-1,3-dicarboxylate (1) were developed. The first synthetic method comprises preparation of the bis-enaminone reagents 2 and 8 and their cyclization with primary amines 3 via double substitution of both dimethylamino groups to give dihydropyridines (DHPs) 4 and 9, respectively. Another variation consists of preparation of the monoenaminone reagents 5 and 10, followed by substitution of the dimethylamino group with primary amines 3, and cyclization of the so formed intermediates 6 with N,N-dimethylformamide dimethylacetal (DMFDMA). In this manner, a library of 46 analytically pure compounds, 24 intermediates 6, 11, and 13, and 22 final dihydropyridines 4 and 9 was obtained employing just a simple filtration workup.

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1,3-Dipolar cycloadditions of racemic (1Z,4R*,5R*)-arylmethylidene-4-benzamido-5-phenyl-3-pyrazolidinon-1-azomethine imines 3 to enantiopure di-(-)-menthyl maleate (4) afforded mixtures of diastereomeric cycloadducts 5/5'-7/7'. Selectivity as well as stereochemistry of cycloadditions were dependent on the substituents at the 1'-Ar residue of dipoles 3. Thus, reactions of dipoles 3a-j with at least one free ortho-position gave either di-(-)-menthyl (1R*,2S*,3R*,5R*,6R*)-3-aryl-6-benzamido-7-oxo-5-phenylhexahydropyrazolo[1,2-a] pyrazole-1,2-dicarboxylates 5/5' (the endo-isomers) and/or di-(-)-menthyl (1S*,2R*,3R*,5R*,6R*)-3-aryl-6-benzamido-7-oxo-5-phenylhexahydropyrazolo[1,2-a] pyrazole-1,2-dicarboxylates 6/6' (the exo-isomers) with syn-oriented 3-H and 5-H, whilst reactions of 4 with ortho-disubstituted dipoles 3k,l gave (1S*,2R*,3S*,5R*,6R*)-diastereomers 7/7'k,l with anti-oriented 3-H and 5-H. Separation of diastereomeric cycloadducts 5/5'-7/7' by crystallization and/or MPLC furnished isomerically pure compounds 5a,b,d,g,5'b,d,h,6c,d,j, and 6'c,d,f and purified mixtures of diastereomers 5/5'=e, 6/6'e,h, and 7/7'k,l in 1-42% yields. The relative configuration of the pyrazolo[1,2-a] pyrazolone structural element in the products 5/5'-7/7' was determined by NMR.

A simple and efficient synthesis of four new substituted pyrimidines, compounds 9a - d, from the title compound 3 is described. Conversion of 3 to methyl (E)-3-(dimethyl amino)-2-(6-methoxy-2-phenyl pyrimidin-4-yl)prop-2-enoate (4), followed by condensation with various dinucleophiles according to the 'enaminone methodology', afforded the target compounds 9 in medium-to-good yields.

Substituted 2,3,5,6,7,8-hexahydropyrazolo[4,3-d][1,2]diazepine-8-carboxylates were prepared in good to excellent yields from ethyl (2E)-3-(dimethylamino)-2-{(4Z)-4-[(dimethylamino)methylidene]-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl}propenoate with 1,2-disubstituted hydrazines by heating in an alcohol.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Combinatorial solution-phase cycloadditions of (1Z,4R*,5R*)-4-benzoylamino-5-phenylpyrazolidin-3-on-1-azomethine imines 3 to beta-keto esters 4 afforded a library of 26 bicyclic pyrazolidinones 5 in 6-89% yields and in 14-100% de. All products were isolated in >90% purity according to 1H NMR, and 25 of them were analytically pure. The structures of cycloadducts were confirmed by NMR and X-ray diffraction. Most of the products were isolated as mixtures of the major (1S*,2S*,3R*,5R*,6R*)-epimers 5 and the minor (1R*,2S*,3R*,5R*,6R*)-epimers 6. Epimerization of cycloadducts 5/6 at the anomeric position 1 in solution was confirmed by 1H NMR.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access the actual ChemInform Abstract, please click on HTML or PDF.